an emphasis on originality, on the need to transcend tired forms and stale conventions

an emphasis on the natural, both in humans and in the physical universe

a more frankly erotic emphasis than was common in much poetry of his time

Many of these traits are clearly visible in the opening lines of "Song of Myself":

I celebrate myself, and sing myself,

And what I assume you shall assume,

For every atom belonging to me as good belongs to you.

I loafe and invite my soul,

I lean and loafe at my ease observing a spear of summer grass.

My tongue, every atom of my blood, form’d from this soil, this air,

Born here of parents born here from parents the same, and their parents the same,

I, now thirty-seven years old in perfect health begin,

Hoping to cease not till death.

Creeds and schools in abeyance,

Retiring back a while sufficed at what they are, but never forgotten,

I harbor for good or bad, I permit to speak at every hazard,

Nature without check with original energy.

Here we see a number of traits already mentioned, especially the emphasis on self; the celebratory impulse; the sense of connection between speaker and reader and the sense that the speaker speaks both for himself and for the reader; the appreciation of nature; the emphasis on the physical, including the physical body; the sense of attachment to America; the autobiographical impulse; the sense of speaking for oneself rather than merely adhering to traditional "Creeds and schools"; the emphasis on "Nature" and, especially, on "original energy." No other American poet had written quite like this before, and few have mastered this style in the many decades since Whitman pioneered it. He was an American original and wrote with a stylistic freedom worthy of an American poet.